I went 1/2 size smaller than what I wear for my athletic shoes. I buy my Nikes in 12. From what I understand, you want them to be fairly tight so that your foot doesn't move around much in the shoe. I got them in 11.5 and probably could have went with the 11. I have to layer my socks when I use them.
Know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own? For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's. 1 Corinthians 6:19-20
I beseech you therefore,brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. Romans 12:1